Photography and other types of optical imaging applications rely on the ability to record the extent of light exposure. Photographic films use light-sensitive silver halide salts that turn dark when exposed to light as a way to record the light exposure. In contrast, digital photography detects and records light exposure information in electronic form. Typically, an electronic photo detector uses either charge-coupled devices (CCD) or CMOS sensors for converting light into electric signals that can be read and stored in a data storage device. The CCD and CMOS sensors require complex electronic circuits and are relatively costly to manufacture. Moreover, it is difficult to reduce the pixel sizes of such sensors to substantially increase their spatial resolution and pixel density.